Title: Electrokinetic pumping of nonpolar solvents using ionic fluid.Abstract: Techniques are generally described that include electrokinetic pumping an emulsion comprising an ionic fluid and a nonpolar fluid to promote flow of the ionic fluid by electro-osmotic flow and drag the nonpolar fluid by viscous drag forces. In some examples, the electrokinetic pump may be utilized to deliver one or more reagents within a fluidic reactor system, such as a micro-scale reactor system. In some additional examples, a reagent may be dissolved in the nonpolar fluid of a first emulsion and pumped through the electrokinetic pump to a mixing channel to allow the reagent of the first emulsion to react with a reagent of second emulsion to form a reactive product. ...

BACKGROUND

Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

Micro-scale reaction systems commonly use electrokinetic pumps to deliver controlled amounts of reagents. Electrokinetic pumps convert electrical potential to hydraulic power. In particular, electrokinetic pumps comprise a channel with spaced apart electrodes disposed at each end of the channel. A polar solvent may be delivered to the channel. When a voltage difference is applied to the spaced apart electrodes, the electrical potential promotes the flow of the polar solvent through the channels.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several examples in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

In the drawings:

FIG. 1 is a schematic illustration of an electrokinetic pump;

FIG. 2 is a molecular diagram for an example ionic fluid;

FIG. 3 is a schematic illustration of an electrokinetic pump;

FIG. 4 is a system diagram; and

FIG. 5 is a flow chart illustrating a method of carrying a nonpolar fluid through an electro-osmotic pump; all arranged in accordance with at least some examples of the present disclosure.

DETAILED DESCRIPTION

The following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative examples described in the detailed description, drawings, and claims are not meant to be limiting. Other examples may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are implicitly contemplated herein.

This disclosure is drawn, inter alia, to methods, systems, devices, and/or apparatus generally related to electrokinetic pumping an emulsion comprising an ionic fluid and a nonpolar fluid to promote flow of the ionic fluid by electro-osmotic flow and drag the nonpolar fluid by viscous drag forces. In some examples, the electrokinetic pump may be utilized to deliver one or more reagents within a fluidic reactor system, such as a micro-scale reactor system. In some additional examples, a reagent may be dissolved in the nonpolar fluid of a first emulsion and pumped through the electrokinetic pump to a mixing channel to allow the reagent of the first emulsion to react with a reagent of second emulsion to form a reactive product.

In some examples, a reactor system may comprise one or more electrokinetic pumps. An electrokinetic pump may include a first channel having an inlet and an outlet, a first electrode positioned proximate the inlet, and a second electrode positioned proximate the outlet. The inlet of first channel may be adapted to receive an emulsion. The emulsion may include an ionic fluid, a nonpolar fluid, and/or a reagent. The electrokinetic pump may be configured to promote flow of the emulsion through the first channel when a voltage difference is applied between the first and the second electrodes. In particular, the voltage difference promotes flow of the ionic fluid by electro-osmotic flow, and as the ionic fluid flows through the first channel, the ionic fluid drags the nonpolar fluid by viscous forces.

In some embodiments, a first emulsion may mix with a second emulsion in a mixing channel. A reagent from the first emulsion may react with a reagent from a second emulsion to form a reactive product. In one example, the reagent in the first or second emulsion may be the nonpolar fluid. In another example, a dissolved substance in the nonpolar fluid of the first emulsion may comprise the first reagent and/or a dissolved substance in the nonpolar fluid of the second emulsion comprises the second reagent. In some examples, a stabilizing agent may be applied to the emulsion to maintain the emulsion. After exiting the electrokinetic pump, the stabilizing agent may be removed from the emulsions and the reactive product may be removed. Additionally, the ionic fluid may be removed and reused.

FIG. 1 is a schematic illustration of a reactor system 100 comprising an electrokinetic pump arranged in accordance with at least some examples of the present disclosure. The example reactor system 100 may be a micro-scale reactor system that utilizes a micro-scale electrokinetic pump to deliver one or more reagents to a mixing zone to form a reactive product. The example reactor system 100 may comprise a first inlet 102 coupled to a first reservoir 103 and a second inlet 104 coupled to a second reservoir 105. A first electrode 114 and a second electrode 115 may be positioned in the reactor system 100 so that the electrode is in electrical communication with a fluid within the reactor system 100. For instance, in some examples the first electrode 114 may be positioned proximate the first inlet 102, and the second electrode 115 may be positioned proximate the second inlet 104. In other examples, the first electrode 114 may be positioned in the first reservoir 103 and the second electrode 115 may be positioned in the second reservoir 105. The first inlet 102 may be in fluid communication with a first channel 106, and the second inlet 104 may be in fluid communication with a second channel 108. The first channel 106 and the second channel 108 may be combined at a first end of a third channel 110. A second end of the third channel 110 may be coupled to an outlet 112. The outlet 112 may be coupled to third reservoir (not shown) or another component in a fluid system (not shown). A third electrode 116 may be positioned proximate the outlet 112 or in some examples, positioned in the third reservoir. Between point A and point B on the third channel 110 comprises a mixing zone. As indicated above, in some examples the reactor system is a micro scale reactor. In these examples, the channels may have a diameter in the millimeters and/or micrometers.

In one example, the first and second reservoirs 103 and 105 may each be configured to mix a respective emulsion comprising an ionic fluid and a nonpolar fluid. That is, the ionic fluid is immissible and unreactive with the nonpolar fluid. The nonpolar fluids may be any liquid or gas that cannot be pumped using electro-osmotic flow. In some examples, the nonpolar fluid comprises an organic solvent, such as hexane, toluene or linear ethers.

In general, when two immiscible materials are mixed to create an emulsion, the emulsion may be unstable and the two materials may separate over time. Thus, in some examples a stabilizing agent may be added to stabilize the emulsion. That is, a stabilizing agent may be added to the emulsion to keep the two fluids in its emulsion state. The stabilizing agent may comprise one or more of a surfactant, a plurality of nanoparticles, such as fumed silica nanoparticles, and/or any other agent capable of stabilizing the emulsion. Example stabilizing agents are described in Bernard P. Binks, et al., Novel Emulsions of Ionic Liquids Stabilized Solely by Silica Nanoparticles, Chem. Commun., 2003, 2540-2541, which is incorporated by reference herein in its entirety for all purposes. In many examples, the nonpolar fluid may comprise a dissolved reagent that is to react with another reagent in the mixing zone between point A and B on the third channel.

In some examples, rather than mixing the emulsion in the first and second reservoirs 103 and 105, the first and second reservoirs 103 and 105 may be adapted to receive premixed emulsions. The first and second emulsions may be mixed in the first and second reservoirs 102 and 104, respectively or may be mixed prior to entering its respective reservoir. The first inlet 102 may be configured to receive a first emulsion from the first reservoir 103. The second inlet 104 may be configured to receive a second emulsion from the second reservoir 105. A power source (not shown) may be coupled to the reactor system 100. The power source may be adapted to apply a voltage differential between the first electrode 114 and the third electrode 116, and a voltage differential between the second electrode 115 and the third electrode 116. For instance, the first and second electrodes 114 and 115 may have a voltage that is higher than the voltage of the third electrode to produce a voltage difference between the first inlet 102 and the outlet 112 and the second inlet 104 and the outlet 112. The voltage difference may be any voltage difference sufficient to promote the flow of the emulsions to the outlet 112.

A first electric potential may be applied between the first electrode 114 and the third electrodes 116 to create an electro-osmotic force adapted to drive polar molecules from the first inlet 102 to the outlet 112. A second electric potential may be applied between the second electrode 115 and the third electrode 116 to create an electro-osmotic force adapted to drive polar molecules from the first inlet 102 to the outlet 112. In particular, the first electrical potential drives the ionic fluid from the first inlet 102 to the outlet 112, and the second electrical potential drives the ionic fluid from the second inlet 104 to the outlet 112. Because the ionic fluids in the first and second reservoirs 102 and 104 each formed a first and second emulsions with a respective nonpolar fluid, the ionic fluids drags its respective nonpolar fluid with it by viscous forces. In one example, the ionic fluid is the dominant material in the first and/or second emulsion. For instance, in one example the amount of ionic fluid in either the first or second emulsion is an amount sufficient to maintain a cohesive conductive path between the electrodes.

As the ionic fluid in the first emulsion drags the nonpolar fluid from the first inlet 102, the first emulsion passes through the first channel 106 and into the third channel 110. As the ionic fluid in the second emulsion drags the nonpolar fluid from the second inlet 104, the second emulsion passes through the second channel 108 and into the third channel 110. While both the first and second emulsion are in the third channel 110, a reactant in the first emulsion may react with a reactant in the second emulsion in the mixing zone between points A and B to form a reactive product. As indicated above, a reactant may be one or more dissolved reagents in the nonpolar fluid or may be the nonpolar fluid itself. In some examples, the reagent may be one or more of Grignards, AlCl3, DCC, or other similar reagents. In some examples, the reagent may be may be water sensitive. That is, water may be a competing reactant to a reagent. In order to control the amount of water in an emulsion, in some examples, prior to mixing the first and second emulsions in the mixing zone, one or both emulsions may be passed through a drying agent to eliminate water in the emulsions. For instance, a drying agent may be provided in first and second reservoirs 102 and 104 or on channels 106 and 108. In some examples, the first and second reagents may pass through microporous silica first to minimize pressure variations in the system.

Once a reaction takes place between points A and B in the mixing zone, the first and second emulsions may exit the system 100 at outlet 112. Upon exiting the system at the outlet 112, the first and second emulsions may be provided to a collection reservoir (not shown). The collection reservoir may be included in the example reactor system 100 or may be separate from the reactor system. In the collection reservoir the first and second emulsions may be broken to separate the ionic fluid from the organic solvent. In some examples, the first and second emulsions may be broken by removing the stabilizing agent. In other examples, the emulsion may be broken by filtration, such ultrafiltration, by adding water to the emulsions, such as when a water soluble ionic fluid is used, by heating and/or cooling the system, or any other method capable of breaking an emulsion. Once the emulsion is broken, the reactive product may be separated from the organic solvent. For instance, in some examples the organic solvent may be removed utilizing stripping techniques, such as by utilizing a vacuum process like rotary evaporation. In other examples, a second solvent may be added the first and second emulsions that precipitates the reactive product, which may then be collected by filtration. The second solvent may be added to the first and second emulsions before the emulsions are broken or after the emulsions are broken. Additionally, the ionic fluid may be separated from the organic solvent and may be recycled and reused. For instance, the ionic fluid may be cycled back through a electrokinetic pump in the reactor system 100 for reuse.

In one example, the ionic fluid comprises butyl methypyrrolidinuum bis(triflimide) (BMP-TFSI). FIG. 2 is a molecular diagram 200 for an example ionic fluid in accordance with at least one example of the present disclosure. The example ionic fluid may be used to form an emulsion when mixed with a nonpolar fluid as described above. Butyl methypyrrolidinuum bis(triflimide) has low water content, low viscosity, and is a simple quaternary ammonium salt and is extremely stable to many different chemical reagents that may be dissolved in the nonpolar fluid. Other possible ionic fluids are described in Marek Kosmulski, et al., Electroacoustics and electroosmosis in low temperature ionic liquids, Cooloids and Surface A: Physicochemical and Engineering Aspects, Volume 267, Issues 1-3, October 1005, p. 16-18, which is incorporated by reference herein in its entirety for all purposes.

FIG. 3 is a schematic illustration of a reactor system 300 arranged in accordance with at least some examples of the present disclosure. The example reactor system 300 includes two separate electrokinetic pumps rather than two combined electrokinetic pumps as illustrated FIG. 1 in the example reactor system 100. The example reactor system 300 includes a first reservoir 302 and a second reservoir 304. The first reservoir 302 may be in fluid communication with an inlet of a first channel 306, and the second reservoir may be in fluid communication with an inlet of a second channel 308. The first reservoir 302 and/or the inlet of the first channel 306 may comprise a first electrode 314 that is configured so that the first electrode 314 may be in electrical communication with a fluid, such as an emulsion, therein. The second reservoir 304 and/or the inlet of the second channel 308 may comprise a second electrode 315 so that the second electrode 315 may be in electrical communication with a fluid, such as an emulsion, therein. The first and second channels 306 and 308 may combined into a third channel 310. The third channel 310 may comprise a mixing zone for mixing reactants provided from the first and second reservoirs 302 and 304. The third channel 310 may be in fluid communication with a fourth channel 326 and a fifth channel 328. The fourth channel 326 may comprise a third electrode 318 and a first outlet 322. The fifth channel 328 may comprise a fourth electrode 319 and a second outlet 324. In some examples, the first outlet 322 is coupled to may be third reservoir (not shown) and the second outlet 324 may be coupled to a fourth reservoir (not shown). In these examples, the third electrode 318 may be positioned in the third reservoir and the fourth electrode 319 may be positioned in the fourth reservoir.

The first and second reservoirs 302 and 304 may comprise a first and second emulsion, respectively, as is described in reference to the emulsions in the reactor system 100 in FIG. 1. A power source (not shown) may be coupled to the reactor system 300 and adapted to apply a first voltage differential between the first electrode 314 and the third electrode 318. The power source may be further adapted to apply a second voltage differential between the second electrode 315 and the fourth electrode 319. The first voltage differential drives the ionic fluid from the first reservoir 302 to the outlet 322, and the second voltage differential drives the ionic fluid from the second reservoir 304 to the outlet 324. The ionic fluids in each of the first and second reservoirs, 302 and 304, drag the nonpolar fluid from its emulsion by viscous force.

In other examples, more electrokinetic pumps may be adapted to move and mix more than two components and thus include more than two reservoirs and corresponding channels. In general the number of reservoirs may depend on the number of reactants to be supplied to the mixing zone for reacting. In some examples, not all electrodes may have a voltage applied so that less than the number of reservoirs comprising an emulsion will be supplied to the mixing zone.

FIG. 4 is a system diagram 400 that may comprise at least one electrokinetic pump arranged in accordance with at least some examples of the present disclosure. The example system 400 may include an input/output device 410, a controller 420, power source 430, at least one electrokinetic pump 440, and a fluid source and collection 450. The controller 420 may be coupled to the input/output device 410, the power source 430, and the fluid source and collection 450. The controller 420 may be adapted to selectively control the amount of fluid delivered to the at least one electrokinetic pump 440 by providing one or more control signals to the fluid source and collection 450. In response to the one or more control signals, the fluid source may provide an emulsion as described above to an inlet of an electrokinetic pump 440 or to a reservoir. The electrokinetic pump 440 may include a plurality of electrokinetic pumps that interact to form a reactor system, such as the reactor system described in FIGS. 1 and 3. Alternatively, more than two electrokinetic pumps 440 may be coupled together to form a reactor system. The reactor system may include any number of channels, electrodes, mixing channels, and/or reservoirs.

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20121206|20120305399|electrokinetic pumping of nonpolar solvents using ionic fluid|Techniques are generally described that include electrokinetic pumping an emulsion comprising an ionic fluid and a nonpolar fluid to promote flow of the ionic fluid by electro-osmotic flow and drag the nonpolar fluid by viscous drag forces. In some examples, the electrokinetic pump may be utilized to deliver one or |Empire-Technology-Development-Llc